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RE: I'm not sure

Posted by Ugly (A) on June 2, 2017 at 10:26:03

In Reply to: I'm not sure posted by Ralph on June 2, 2017 at 09:36:04:

My servo attempts to bring the preamps output offset to the same potential as the midpoint of the cartridge coil by stripping out the low frequency from the output and (negative) feeding it back.

All I meant by "two matched resistor method" is by placing two matched resistors in series across the coil outputs, the midpoint between the resistors may be usable as the servo reference.

Unless there is some better way to find the cartridge midpoint than using two "matched" resistors which will never actually be matched in the real world....I'd love to find a better way but have not come up with anything.

Sorry that was unclear.

I'm at work now. I can hack up a schematic when I get home and post it.

My servo circuit uses more than two poles. It is based on a weird circuit I found on the internet in an old LT app note and mixed in a bit of my own special sauce but all seems to simulate nicely. I get very deep audio band rejection but takes maybe a bit too long to settle. I will need to fine tune it when I get hardware in hand, ie this is all simulation at this point.

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